The structure, dynamics, thermodynamics and spectroscopy of molecules and groups of molecules are determined by their underlying potential energy surface. My research interests are primarily focussed on the accurate calculation of structure and spectroscopy from the potential energy surfaces of hydrogen-bonded clusters and gas clathrate hydrates. More information can be found below, or by viewing my publications.

Gas hydrates are crystalline inclusion compounds that consist of a guest atom or molecule trapped inside a network of rigid polyhedral cages. In recent times, interest in the properties of gas hydrates has increased due to the energetic and enviromental implications of large deposits of methane hydrate found on the seafloor.

We are also interested in using molecular dynamics simulations to study the structure and stability of gas hydrates. We have developed a polarizable force field that explicitly includes contributions from exchange repulsion, dispersion, charge penetration, and multipole electrostatics to describe the interaction between bromine and water. This force field was combined with a polarizable force field for water and used in molecular dynamics simulations to calculate the relative energetics of three bromine clathrate hydrates. We found that all three structures were close in energy, supporting experimental measurements by the Janda group that provided evidence for three different bromine hydrate crystal types.

It is likely that hydrogen bound water clusters are important absorbers of solar radiation. Before their role can be quantified, their spectral identification and characterisation is essential. As the majority of the Sun's radiation is produced in the ultraviolet, visible and near-infrared regions of the electromagnetic spectrum, the vibrational overtone and electronic transitions are of primary interest.

We are interested in developing vibrational Hamiltonians to describe the vibrational motion of clusters such as the water dimer. Coupled with this is an interest in obtaining accurate potential energy and dipole moment surfaces from ab initio calculations to provide parameters for the Hamiltonian. Previous results were in good agreement with experimental studies. In addition, a collaboration with atmospheric scientists enabled us to show that the water dimer is an important contributor to the water vapour continuum.